Loading machine having a hydraulic control system for traction means



p 1952 A. L. LEE 2,611,444

LOADING MACHINE HAVING A HYDRAULIC CONTROL SYSTEM FOR TRACTION MEANS Original Filed April 10, 1944 5 Sheets-Sheet 1 Adv/m Sept. 23, 1952 A. LEE 2,611,444

' LOADING MACHINE HAVING A HYDRAULIC CONTROL SYSTEM FOR TRACTION MEANS Original Filed April 10, 1944 3 Sheefgs-Sheet 2 q I04 '03 Q 3 INVENTORJ ARTHUR L. LEE,

HTT'v Sept. 23, 1952 LEE LOADING MACHINE HAVING A HYDRAULIC CONTROL SYSTEM FOR TRACTION MEANS Original Filed April 10. 1944 3 Sheets-Sheet 3 Patented Sept. 23, 1952 LOADING MACHINE HAVING A HYDRAULIC CONTROL SYSTEM FOR TRACTION MEANS I Arthur L. Lee, Upper Arlington, Ohio, assignor to The Jeffrey Manufacturing Company, a cor-- poration of Ohio Original applications April 10, 1944, Serial No..

530,361, now Patent No. 2,589,827, dated March 18, 1952, and December 3, 1947, Serial No. 789,383, new Patent No. 2,527,943, dated October 31, 1950. Divided and this application June 23, 1950, Serial No. 169,858

This invention relates to a hydraulic system and valve therefor which while specifically designed for a loading machine are in certain broad aspects equally applicable to vehicles and 4 Claims. (Cl. 180-43) Fig. 10 is a side elevational view-with parts in section showing the operating lever of the last or left hand valve of the valve assembly of Figs. 3+5 which has a different function from the other machines other than loaders. 5 valves.

An object of the invention is to provide a This application is a division of my c0-pend loader including a hydraulic system in which ing applications Serial No. 530,361, filed April 10, there are hydraulic motors for operating trac- 1944, for a Loading Machine, now Patent No. tion wheels, the system providing for reverse op- 2,589,827, dated Mar. 18, 1952, and Serial No. eration of the traction wheels in parallel or in 789,383, filed December 3, 1947, now Patent No. tandem relation. 2,527,943, dated October 31, 1950, for a Hydraulic Another object of the invention is to provide Valve and System. It is to be understood that a mining machine with a hydraulic system inthe construction and operation of the loader of eluding related control and characteristic conthis application follows that of my first parent trolling valves the characteristic being controlled application, above identified, and that only the being in the specific instance the fluid pressure subject matter pertinent to the present invention which is delivered to the hydraulic motors, the is disclosed in detail herein. arrangement providing for control first of the Briefly described, the loader seen in Fig. l of connection of the motors to the hydraulic system the drawings includes a main frame H] which inand thereafter a progressive variation of the cludes a pair of spaced apart longitudinally excharacteristic of the fluid or specifically the prestending upstanding side plates 1 l and I2 whichsure. are reinforced and held in spaced relation by a In a more specific aspect of the invention a plurality of spaced U-shaped brackets indicated single operating lever is employed to carry out at I3 each of which is welded to the side plates these functions and in a broader aspect of the II a d Throughout the aJ'O por ion of its invention it relates to such a hydraulic system length, th frame 10 includes in its p n b for general application. tween the upstanding side plates l l and 12 a pan Other objects of the invention will appear heretrough M t S d edges of which are welded inafter, the novel features and combinations to the plates II a i2 and which constitutes a being set forth in the appended claims. conveying trough through which coal or other In t accompanying drawings: material being conveyed by the loader is scraped i 1 is a plan View of a loading machine by an endless chain flight conveyer mechanism [5. bodying my invention; The main frame 10 to a large extent constitutes Fig. 2 is a schematic piping diagram of t a frame of an extensible conveyer it that extends hydrauli y tem of the loading machine; throughout the length Of the loading machine Fig. 3 is an elevational view of the hydraulic and 0f Wh10h pan is a P and n y n control valve assembly of the hydraulic system mechamsm constltutes the means for pi with the operating mechanism of one of the valve materialfront p rtion of the extensible operating levers Shown in t conveyer It includes a frame, indicated generally Fig. 4 is a sectional elevational view of the 40 by h reference character H. w ich telescopes bank of valves of Fig. 3, with the pressure control Withln the main frame and is p ed to be valve shown in 1 t adjusted rectilinearly with respect thereto to in- 5 is a Sectional View taken on t line 5 5 crease appreciably the overall effective length of of Fig. 3, showing the pressure valve in section the eXtenSlble v y r l and also showing in section a portion of one of h adjustable frame 1 includes a itudithe operating levers; nally extending column or trough portion 18 Fig. 6 is a side elevational view of one of the Whlch 1S slldably ained between the side operating levers of the valve assemblies of Figs. p a es H and I2 of the main frame in. Ad- 3 and 5; jacent its forward end the frame I! is provided Fig. 7 is an elevational view of one of the parts With a gathering head l9 including a forwardly or members of the valve assembly of Figs. 3 and 5; d downwardly slop gathering p a 0v Over Fig. 8 is a sectional view taken on the line 8-8 which coal or other material is gathered from of Fig. 5, looking in the direction of the arrows; the mine room floor by a pair of endless chain Fig. 9 is a sectional view taken on line 9-9 of and flight gathering conveyers 2] and 22. The Fig. 5, looking in the direction of the arrows; and endless conveyer mechanism l5 travels between a head shaft on the gathering head [9 and a foot shaft at the rear end of the main frame and over appropriate guide and drive sprockets on the trough or column [8 and the main frame I 0, respectively, in a manner disclosed in full detail in my parent case, Serial No. 530,361, now Patent No. 2,589,827, above identified. The construction is such as to permit rectilinear telescopic adjustment of the front frame l1, column or trough l8 and gathering head I9 while providing for a continuous working run of the conveyer mechanism through the trough orpan i4 and an overlapping pan or trough 23 which overlaps said trough I4 and is attached to and reciprocates with the frame I1, the trough 23 forming in effect a continuation of guiding side walls of the trough l8.

The loader is supported on four rubber tired wheels so that it may be transported under its own power from place to place. The four wheels ing hydraulic piston motors 26 which are seen in Fig. 2 of the drawings.

When the machine is performin a loading operation its rear and may be supported for pivotal swinging movement through a ball and socket support, one member 21 of which is attached to the rear end of the main frame adjacent the foot shaft of the conveyor mech anism I 5 and the other member of which may be carried by a receiving conveyor in the mine room, not shown, and the wheels 24 will be lifted off the ground by the hydraulic cylinders 26 to provide for swinging of the main frame l0, and thus the complete loader, in a generally horizontal plane on an axis through the member 21. The other two wheels of the loaderinelude front supporting and traction wheels 28 and 29 which may be adjusted to parallel positions, as illustrated in full lines in Fig.1 of the drawings, or they may be adjusted substantially to tandem positions, as illustrated in dotted lines therein, in which tandem positions they are adjusted to swing the loader about the axis of the member 21 so as to position the gathering head is opposite coal or other material which is to .be loaded by rectilinear frontal attack feeding movement of said gathering head I9.

The front frame 1 l, as previously stated, is carried for rectilinear sliding movement in the main frame iii and this movement, by which the gathering head I9 is fed to dig into and load loose or semi-compact coal, is carried out through mechanism which is shown and described in full detail in my parent application, Serial No. 530,361, now Patent No. 2,589,827, above identified, by means of a sprocket 30 which is driven through an appropriate driving chain from a reversible rotary hydraulic motor 31 which is provided with built-in speed reducing gearing.

The primary source of power for the various power operated devices on the loader is an electric motor 32 which is mounted on one side of the main frame H]. The rotor or armature shaft of motor 32 drives a hydraulic pump 32 which is the source of hydraulic fluid pressure for the hydraulic system which is illustrated particularly in Fig. 2 of the drawings and it also drives, through suitable clutch and transmission mechanism which is shown and described in my parent application, Serial No. 580,361, above identified, the endless chainand flight conveyer mech- Ill anism l5 and the gathering conveyers 2! and 22.

The wheel assembly 28 is on the right hand side of the loader as viewed by an operator seated upon an operators platform 34 which is carried by the main frame in opposite the electric motor 32 and the wheel assembly 29 is on the left hand side. These two wheel assemblies are thus on opposite sides of the main frame l0 and during transportation or rectilinear travel of the vehicle they act to drive it generally in the manner of an ordinary automobile or other power driven steerable vehicle. In other words, these two assemblies travel parallel paths and have a common axis of rotation normally transverse to the longitudinal axis of the main frame It. Wheels 28 and 29 .are each driven by a reversible rotary hydraulic motor 35 through reduction gearing. The assemblies which include the wheels 28 and '29 and pivotally mount them to the main frame l8 are interconnected by mechanism, not herein shown, so that the wheels 28 and 29 may be locked in their parallel positions or unlocked to swing together to their tandem positions and be relocked and vice versa. Swinging movement together of the assemblies which include the wheels 28 and 29 may be accomplished by releasing the locking interconnecting mechanism and operating the reversible motors 35 to drive the wheels both in the same direction, the direction depending upon the position to which the wheel assemblies are to be swung, and the interconneeting mechanism is locked when the assemblies reach the desired position. The assemblies which include the wheels 28 and 29 and pivotally mount them to the main frame [0 are also provided with means whereby the wheels may be vertically adjusted with respect to the main frame In by piston motors 36 for providing for the vertical adjustment of the elevation of the forward end of the gathering head [9 as well as the pressure thereof on the mine floor when it is resting thereon.

As best seen in Fig, 1 of the drawings, there is a platform 31 adjacent and rigidly attached to the front end of the main frame I0 which extends laterally to both sides thereof. On one side this platform supports the previously described hydraulic motor 3|. on the other side of the platform 31 is a tank 38 for hydraulic fluid of the hydraulic system which is preferably oil. Leading from the tank 38 is a feed pipe conduit 39 (Fig. 2) which leads to pump 33. Leading back to the tank 38 is a seepage, Joy-pass, or return conduit 40, by which hydraulic fluid is returned thereto. The pump 33,, of course, produ-ces hydraulic fiui'd under pressure and delivers it by way of an outlet pipe or conduit 4! to a valve assembly including a variably operable pressure relief valve 42 and a bank of four-way spool valves designated generally by the reference character 43. i As illustrated particularly in Fig. l of the drawmgs the Valves 42 and 4-3 are located adjacent the 'oper'ators platform 34 where the individual valves of the bank '43 may be readily operable by an operator on said platform; The hydraulic systemas well as the detailed structureo'f the valves 42 and 43 as elements of the loader and the hydraulic system and the valve 43 per se are important features of my invention. The structures of the valves 42 and 43 will be describedin detail hereinafter.

At the moment'it is sufiicient to point out in connection with Fig. '4 that there are six slide spools in the bank "of valves '43. The first spool on the right hand side, as viewed in Figs. 2 and 4, controls the motors or jacks 26 which raise and lower the steering wheels 24 which are connected in parallel over obvious pipes or conduits and by shifting this spool in reverse directions from the neutral, the two motors or jacks 26 may be operated in reverse directions. When said spool is in its neutral position these two motors are locked. The second spool from the right provides equivalent control for the single double acting steering motor or jack 25. The third spool from the right in practice is employed as a three-way valve rather than a four-way valve and. it controls the flow of fluid over obvious conduits to the hydraulic piston motors or jacks 36 in parallel which motors or jacks are single acting rather than double acting and are operated for adjusting the elevation of the loader head 19. The fourth spool from the right controls the reversely operable rotary hydraulic motor 3! which feeds the gathering head [9 by adjusting the longitudinally extensible conveyer Hi. This is a fourway valve and conduits are provided extending from it to operate the motor 3| in reverse directions. There is also a third conduit extending from the motor 3| which is a branch of the return or relief conduit 49 and thus receives any leakage of the motor 3| and returns it to the tank 38. The fifth and sixth spools of the bank of valves 43, as viewed from the right, cooperate to provide for operation of the two hydraulic motors in parallel so that said motors 35 may be operated to drive their associated wheels 23, 29 either to move the loader rectilinearly in reverse directions or, in other words, with said wheels in parallel when traveling along parallel paths or to operate said motors 35 in parallel to drive said wheels 28, 29 in tandem, in reverse directions. The particular structures of these two spools and associated passageways and conduits will be described in complete detail hereinafter.

It may also be mentioned that leading from each of the motors 35 is a branch'of the return conduit 49 so as to take the leakagetherefrom. The conduit 49 also extends from the left hand side of the bank of valves 43 and it may be stated that when all of the spools of this valveare in normal condition they provide a no-load by-pass so that the oil can flow freely from the pump 33 to the conduit 49 and back to the tank 38. The conduit 40 also has a branch leading directly to the variably operable pressure relief valve 42.

Attention is now directed to Figs. 3 through 9 of the drawings and to the structures of the variably operable pressure relief valve 42 and the bank of spool valves 43. It may be stated as a prelude to the detailed description of these valves that the pressure relief valve 42 acts not only as a safety valve against excessive pressures in the hydraulic system but that it also has the very important function of adjusting variably and progressively a variable characteristic of the hydraulic fluid and specifically the pressure at which said hydraulic fluid will be discharged when the system is in operation.

The parts are so arranged that by operating a single lever a selected one of the five right hand spools, as viewed-in Fig. 4, may be operated first to effect a connection between the hydraulic fluid under pressure and the particular hydraulic motor or motors selected for operation. As the operating handle is further operated after the spool is adjusted the pressure of the fluid which is delivered to the selected motor is progressively increased as the handle is progressively moved beyond, the initial position. This is a matter of considerable practical importance particularly in a loading machine as it is applied to operate the head feeding motor 3| or traction wheels 28, 29

or, in other words, to operate the reversible roa for a very smooth operation together with safety.

The operator may not have excessive torque in starting the operation but if greater torque is needed than that when the operation is started it is readily available.

Referring first to the details of the bank of valves 43, as seen in Figs. 3 and 4, this bank includes a main body or casing 44 provided with six vertical bores which receive the six spools, only the last two of which will be described in detail and which are designated by the reference characters 45 and 46. As clearly illustrated in the drawings, hydraulic fluid delivered from the pressure relief valve 42 to the valve bank 43 is delivered to a central two-arm passageway 41 and with all the spools in neutral positions this passageway extends by duplicated individual steps through the main body 44 until it is dumped from the central chamber 48 adjacent the spool 45 by way of parallel passageways 49 which dump into parallel top and bottom tank or drain passageways 59, both of which are common to the tops and bottoms of all of the spools. These two passageways 59 are interconnected adjacent the left hand end of the body or casing 44 and are directly connected with the previously mentioned drain conduit or pipe 40-. The bottom passageway 50 is formed in part in a removable bottom plate 5| which is removably attached as by machine screws (not shown) to the casting 44 and may be considered as forming a part of said body 44. The spool 45 extends into one of the previously mentioned bores in the casting 44 which is designated by the reference character 52. This bore is of substantially uniform diameter throughout its entire length from the top of the casting 44 into the bottom passageway 50. Cooperating with the bore 52 are top and bottom motor chambers or ports 53 and 54, respectively, which are connected with the conduits leading to the upper hydraulic motor 35, as viewed in Fig. 2 of the drawings. The bifurcated central passageway 41 associated with the bore 52 is similar in construction to all the others to the right thereof in said casting 44 and it terminates in upper and lower chambers or ports 55 and 5B, respectively.

The spool 45 is provided with an upper land or barrel 5!, a lower land or barrel 58 and a central or intermediate land or barrel 59, said spool 45 being of reduced diameter between land or barrel 59 and the other two lands or barrels5l and 58, as clearly illustrated in Fig. 4 of the drawings.

The spool 45 extends into a uniform bore 60 in the casting 44 and this bore and associated ports and passageways as well as spool 46 are of different structure from the spool 45 and bore 52 which in general is substantially the same as each of the other spools and bores, respectively, of the bank of valves 43. This difference is beings.

"by the valve '46, 60. It may be stated that the function of the valve 416, :6-0 is to control that portion of the hydraulic circuit individual to the two hydraulic motors '35 so that the wheels 28, 29 will rotate selectively either in parallel or, in other words, along parallel paths or in tandem for the purposes previously described.

In certain broader aspects of the invention it may be considered that the valve 46, .60 provides for the operation of the two motors 35 selectively so that they operate either in a like or similar .manner :or in :an unlike or dissimilar manner or, in other words, so that they rotate selectively in the'sam directions, that is, both cloclmrlse :or both counter-clockwise -'or in opposite directions, that is, either one clockwise while the other rotates counter-clockwise.

"The valve 45, 52 operates in conjunction with the valve 56, 60 so that the two motors .35 considered together'may be reversely operated .regardless of whether the wheels are rotating in tandem or in parallel or, in other words, regardless of whether the :motors are operating in a alike-tor in an unlikemanner.

Adjacent the central portion of the bore 50 is a chamber or :port 6| and unlike the somewhat :similar chamber or port 4B chamber 6| is connected by a pipe or conduit directly to one of'the motors 35. In other words, it is connected to 'one of the two pipes at the side 01' low'ermotor 35, as viewed in Fig. 2 of the drawings. Below the chamber or port 61 is a chamher or port -62'whi'ch,-of course, like chamber 6| communicates with the :bore '59 and is connected by a passagewayv to the motor chamber or port 54 of valve 115, 52., Alsocommunicating with the bore Gfljand positioned below chamber or port $2 is a chamber or port ii-3 which connects with the other pipe or conduit leading to thesicle of theilower motor 35, as seen in 'Fig. 2 of'the draw- Directly'above the chamber 6! is .a chamber-or port -64 incominunication with the bore 6:] which chamber 84 is connected-by a passageway to the previously describedtopmotor chamber 53. Directly above the chamberfidand communicating with the bore 60 is another motor chamber or port BSwhich-is connected by a passageway lit to th previously described motor chamber-6'3.

The valve spool 48 has three lands-or barrels including central land or barrel -67, upper land or. barrel-B3 .and lower lander barreI' B-Q.

'l-he spool 45 dikeall of theotherz-spools to the rightof it, =as'viewed'in Fig. 4, is a three-posi- .tion spool and each of these spools -is shown in its :normalor neutral position which provides a no-loa-d by-pass .through passageways 4'1 and to g the (central chambers of each, similar to the central chamber -48, by virtue of the fact that the central lands or=barre1s similar to that at 59 of spool 45 are relatively short in length and the .reduced portion of each of said valve spools similar to spool 45 provides an obvious passageway between the upper and lower arms of successive passageways 41 into thesuccessive central chambers similar to that at '48. As previously described, chamber 43 dumps directly to the tank or drain passageways SO by way of passageways 49.

Assuming that the valve spool 46 is in the position illustrated which is one of its normal positions and the valve spool 45 is shifted upwardly, the hydraulic fluid delivered to the upper arm of the associated passageway will be directed by the lands 5-! and 59 to the motor port 53. The hydraulic fluid under pressure will thus flow through th conduit which is connected with motor port :53 to the upper motor 35' of Fig. 2, the return fluid from said upper motor 35 returning to the lower motor port 54 which under these conditions communicates with the lower tank or drain passageway 50 by way or the lower portion of bore 52. This will, of course, cause rotation of the upper motor 35 of Fig. 2 in a predetermined direction. The pressure of this hydraulic fluid and thus the torque developed by said motor 35 may be progressively adjusted in a manner hereinafter described.

The lower hydraulic motor of Fig. 2 is also connected in parallel with the upper motor 35 and the parts are so connected that with the valve spool 45 in the position illustrated, the two motors =35 will rotate their associated wheels 28, 29 along parallel paths. The hydraulic path by which these two .motors :35 :are connected in parallel is provided by virtue of the fact that motor port 53 is always connected to previously described port '54 associated with spool 48 and with said spool 46 in the position illustrated in Fig. 4 this hydraulic path or passageway extends from chamber 64 through bore 63 to chamber 65, then through passageway 66 to motor port 63 which :is connected with one of the conduits of lower motor 35 0f Fig.2, as previously described.

The other conduit of said lower motor 35 .extends as above described to its port 6| which is now connected through bore 60 to chamber 62 which is permanently connected to the motor chamber 54 which under the assumed conditions (with spool 45 lifted) is connected with lower drain or tank passagway 50, as above described. In other words, thetwo hydraulic motors 35 are hydraulically connected in parallel under the assumed conditions and these two motors drive their associated wheels '28, 29 along parallel paths to move the vehicle forwardly. Undersuch conditions, considering each of the motors individually, one of them rotates in a clockwise direction and the other in a counter-clockwise direction when viewed from directly in front-of each wheel driven by the particular motor.

If the valve spool 45 is returned to its neutral position, asillustrated in Fig. 4, the two motors '35 .willbelockedagainst rotation in eitherdirection. If said .spool 45 is then moved downwardly the two motors.35 will reverse their directions of rotation, driving the wheels 28, 29 along parallel paths to reverse the direction of travel of the vehicle. Itisbelievedthecircuits created are obvioussince under these conditions motor port 54 .is connected to the pressure passageway 4-1 and .motor .port 53 .isconnected to upper drain passageway 5.0.

.Itwillbe seen that when the wheels 28, are in their .tandem position that because each of them has been swung .forwardlyinopposite directions abouttheir respective perpendicular spaced axes thatthedirection ofoperation of one of the wheels and consequently its driving motor 35 must be reversed with respect to the other to swing the loader about'its axis of the mounting memberllso that thedriving action of the wheel 18 will notopposethedriving action of the wheel 29 and-vice versa. Accordingly when the spool is moved downwardly from :the position illustrated in Fig. 4,:the:relativedirection of rotation -.of thetwo-motors=35is reversed'fromrthat just described. This is the arrangement of :the valves .employed .when the wheels '28, .29 are in their tandem position indicated in dotted lines in Fig. 1 and it is desired to swing the loader in either of the two reverse directions. The effect of the adjustment of the spool 46 hydraulically is to shift the previous connection of the motor chambers 53 and 63 in parallel and the motor chambers 54 and GI in parallel to one in which a reverse direction exists and motor chamber 53 is connected in parallel with motor chamber GI and motor chamber 54 is connected in parallel with motor chamber 63. This is eflected in a manner which is believed evident in that by moving spool 46 downwardly the restricted portion between lands 51 and 59 will interconnect chambers 62 and 63 while the restricted portion between lands 61 and 68 will interconnect chambers 64 and BI.

It is, of course, obvious that when the wheels 28, 29 are in their tandem positions, as shown in Fig. 2 in dotted lines, and the valve 46 is adjusted so as to operate them in this position, they may be driven in reverse directions. The two motors 35 under these conditions, while reversible together, each operate in a similar manner or in th same direction such as a clockwise direction or a counter-clockwise direction.

It is thus evident that I have produced a novel combination of valves as well as a novel hydraulic system and in addition a novel combination of parts in a loading machine or the like which provides for extreme flexibility of operation with a pair of hydraulic motors to perform different functions.

It may be further mentioned that adjacent the top of each of the spools illustrated in Fig. 4 of the drawings there is a hydraulic seal (not shown) preventing leakage of fluid from the casting 44.

Attention is now directed particularly to Figs. 3 and 5 of the drawings and to the structure of the pressure control valve 42. As illustrated in Fig. 3, the valve 42 is mounted on a short pipe 18 threaded into the casting 44 which pipe directs hydraulic fluid to the first passageway 41 (Fig. 4) This pipe physically supports the valve 42 from the valve bank 43. To prevent turnin movement of the valve 42 a bracket 1| has an arm which extends in front of the bottom portion of valve 42 and is attached by a pair of screws to the casting 44. Removal of the bracket 1| will permit screw threaded removal of the valve 42. Said valve 42 comprises a main body or casting 12 which is provided with a screw threaded inlet port on the right hand side, as viewed in Figs. 3 and 4, which is connected to the conduit 4| (Fig. 2) leading from pump 33 and which communicates with a central chamber 13 formed in the casting 12. From the chamber 13 the hydraulic fluid under pressure communicates directly with the pipe 10 and is thus fed to the passageway 41. As previously mentioned, the function of the valve 42 is to control the pressure of the hydraulic fluid delivered to the hydraulic motors, or, in other words, delivered to the bank of valve 43: To this end there is an upright cylindrical bore 14 which receives a piston 15 having at its bottom an integrally formed by-pass valve cone 16 adapted to cooperate with a seat ring 11 to control the amount of fluid which is discharged from the chamber 13 through the bottom discharge cham her or port 18 which is directed to the drain pipe 48, illustrated in Fig. 2 of the drawings. The pressure of the hydraulic fluid in the chamber 13 is controlled by the size of the by-pass opening provided by the by-pass valve 16-11 and in operation the piston 15 will float under the control 10 of the hydraulic fluid in a manner adjusted by the operator to maintain a hydraulic pressure in chamber 13 at any value from substantially zero to a very high value such as 1200 pounds per square inch or even higher, if desired. In other words, just enough hydraulic fluid is by-passed from chamber 13 to maintain any selected pressure therein and the value may be adjusted over the range indicated. This, of course, has the inherent feature of acting as a high pressure relief valve for the hydraulic system. To effect this automatic but adjustble control, the piston 15 is provided with a very small bore 19 which extends completely through it so that the hydraulic fluid under pressure in the chamber 13 will flo-w through the bore 19 and be present in the bore 14 above said piston 15. As a consequence the only pressure difference between the top and bottom of the piston 15 win be the pressure drop through the bore 19 which will be a function of the flow rate therethrough. The pressure in the bore 14 above the piston 15 is transferred upwardly by the hydraulic fluid through a bore formed in a removable cap or head 8| attached to the casting or body 12 by machine screws (not shown). A

constriction member 82 is placed in the bore 80 so that in case of a fluid flow through said bore 89 it will produce a pressure drop, dependent upon the rate of such fluid flow.

Bore 80 has a horizontal as well as a vertical portion, the horizontal portion of which provides a discharge port into a chamber 83 which is controlled by a ball 84, thus providing a ball check valve. The ball 84 is compressed by a spring 85 in a valve closing direction. The tension of spring 85 is variably adjustable by a reciprocally adjustable plunger 86 mounted in the head8| and extending through stufling box 81. Adjustment of the plunger 86 will adjust the tension of the spring 85 and consequently adjust the pressure necessary to unseat the ball 84 which determines the pressure of the hydraulic fluid in the main chamber 13 of the pressure control valve 42. Mechanism by which the plunger 85 is adjusted is described in detail hereinafter.

Whenever the pressure in the bore 88 is sufiicient to unseat the ball 84, it is obvious that hydraulic fluid under this pressure will flow into the chamber 83. Said hydraulic fluid in chamber 83 is free to discharge into the by-pass chamber or port 18 through an open port 88 formed in the bottom of chamber 83 which communicates with a central bore 89 in the piston 15 over an obvious passageway in which is a fairly light spring 98 which urges the piston 15 downwardly and thus urges the by-pass valve 16-11 into valve closing position.

The operation of the pressure relief valve 42 is as follows: Assuming that the spring 85 is tensioned so that the ball 84 will open at a pressure of 500 pounds per square inch, as long as the pressure in chamber 13 is below 500 pounds the ball 84 will remain seated and consequently there will be no fluid flow into chamber 83. Because of this fact there will be no fluid flow through bores 19 or 80 or through constriction 82. Consequently the pressure on opposite sides of the piston 15 will be equalized and the spring 90 will maintain the by-pass valve 16--11 closed. Should the pressure in chamber 13 exceed 500 pounds per square inch, ball 84 will be unseated and there will be a flow of hydraulic fluid into the chamber 83 and through port 88 and bore 89 to the by-pass chamber 18. This flow of fluid will create a pressure drop through restricted 11 bore I9 so that the pressure on the bottomthereof will be greater than the pressure on top. As a consequence the by-pass valve IS-IT will unseat in response to a lifting of the piston 15 and sufficient hydraulic fluid will be by-passed from chamber 73 to reduce the pressure therein.

Under normal operating conditions, the valve 42 will operate with the piston I in a floatin condition by-passing just enough hydraulic fluid to maintain the preselected pressure in the main chamber I3.

It is obvious that by adjusting the plunger 86 and thus the compression of spring 85, this pressure may be varied progressively and continu: ously from any desired minimum to a maximum value. of the hydraulic fluid which is controlled by the valve 42 is its pressure characteristic. Within certain broad aspects of my invention some other characteristic of the hydraulic fluid such as the rate of fiuid flow might be controlled by said characteristic control valve 42. However, in the instant invention since it is the torque of the motors and particularly the motors 3I and 35 which are to be controlled, it is the pressure characteristic of the hydraulic fluid which is so controlled.

As previously suggested, the Operating mechanism for the first valve spools counting from the right, as viewed in Fig. 4 of the drawings, is reproduced except for certain common operating mechanism, but the operating mechanism for the spool 46 is entirely independent of the others It will be described first and is illustrated in detail in Fig. of the drawings.

Mounted on the left hand end of the casting 44, as viewed in Fig. 3, is a bifurcated bracket 9I (see Fig. 10) the two spaced arms of which extend forwardly and carry a pivot pin 92. Pivotally mounted on the pivot pin 92 is an operating handle 93 which extends forwardly and downwardly in either of its positions of adjustment and which at its upper end terminates in an arcuate plate 94. Extending to the right of the arcuate plate 94, as viewed in Fig. 10, the handle has an integral plate and arm 95 which is located inside the two arms of the bracket SI and has a hole providing pivotal connection with the above mentioned pivot pin 92. The plate 95 carries a hardened segment 98 formed integral therewith which is provided with a pair of spaced notches adapted to receive selectively a spring pressed detent 97 carried between the spaced arms of bracket 9 I.

As previously mentioned, the spool 46 has only two positions and so the detent and notches in the segment 96 cooperate to locate it properly in either of .these two positions. The upper arm of the plate 95 extends in a downwardly sloping direction and carries a pivot pin 98 in its forward bifurcated end which has a sliding contact with a transverse notch 99 formed in the upper end of the spool 46. It is thus manifest that up and down or swinging movement of the handle 93 will produce up and down adjustment of the piston or spool 46.

The other five sliding spools including spool 45 are provided with similar operating handles which differ materially from that just described since they are moved not only to shift the spools but to operate after the spools have been shifted from their neutral positions in either of the two reverse directions to adjust the pressure control or relief valve 42 and thus adjust the pressure of the hydraulic fluid delivered to the selected It is thus evident that the characteristic 12: motor or motor whose control valve is actuated. The structures of these operating levers will be seen particularly by reference to Figs. 3, 5, 6, 7,. 8 and 9 of the drawings.

Adjacent each spool, such as spool 45, there is a bracket I00 having a pair of spaced arms. which bracket is attached by screws to the main casting 44' (see Fig. 8'). arms of said bracket I00 is a pivot pin IOI upon which is pivotally mounted an operating handle I02 by means of a pair of spaced upright webs I03 formed integral therewith and also integral with an arcuate plate I04. Also pivotally mounted on the pin IOI is a forwardly extending. downwardly sloping operating lever I05 which is bifurcated at its lowerend (see Fig. 8) and: is provided with a cross-pin. I06 which extends into an operating groove in the upper end of the associated valve spool, similar to the pin arrangement 98-99, above described in connection with the operation of Fig. 10.

As clearly seen particularly by reference to Figs. 3, 7, 8 and 9, at its. left hand end the arm I05 has as, an integrally formed part thereof. a pair of downwardly extending laterally spaced plates or webs I0! which are also pivoted to the pin I0 I. Between these spaced plates I01 is a washer I08 carried on the pin IOI which acts as a spacer for a coil centering spring I09. The

convolutions of spring I09 are wound around the washer I08 and the free ends thereof extend forwardly or to the right, as viewed in these figures of the drawings, the lower one, as viewed in Fig. 8 of the drawings, extending over an integral lug or abutment I-I0- whichextends inwardly from the lower plate I01, as viewed in,

Fig. 8, and also over transversely extending pin III carried by the bracket I00 and extending between the two spaced apart arms, thereof. The other or upper free end of the spring I09, as viewed in Fig. 8, extends forwardly below anintegrally extending lug I I2' formed on the upper plate I01 and also below the pin I I I. The spring I09 is normally biased sothat the free ends thereof exert opposing forces on opposite sides of the pin IIi. maintain the lever I05 in the neutral position which is illustrated in the drawings and movement thereof to either of the reverse operating positions will be counteracted by the spring I09 in an obvious. manner, thus returning each of the spools in question to its normal position whenever the operating handle I02 is released.

The operating connection between the lever I05 and the handle I02 is a flexible one and provides for the progressive movement of the handle I02 in either of its reverse directions beyond that which is required to shift the spoolssuch as spool 45. This connection includes an operating rod II'3 housed within the handle I02 which is hollow, rod II3 having a head II4 on its outer end and threading into a head II 5' on its inner end. The head II5 slides through an opening of an abutment ring IIG fastened to the inner walls of the opening in handle I02. Surrounding the rod II3 is a coil spring 1' normally under compression which abuts freely slidable washers Ii 8 and H9 at its opposite ends, which washer I I 8 abuts a shoulder formed in the opening of handle I02 and which washer II9 abuts thering H6. The head H5 is pivotally connected to a connecting link I20 which in turn is pivotally connected by a pivot pin I2'I to the rear end of the spool operating lever I05.

During the first movement of the handle I02 Extending between. the

As a consequence they tend to from its normal position in either of its reverse directions, the spring II! and its associated apparatus is Without particular significance and the spool operating lever I moves as a unit with the handle I02. Further movement of the handle I02, however, in either direction will not produce any further movement of the spool operating lever I05 and this will be taken care of by compression of the spring III under the influence of the rod II3, the heads H4 and H5 and the washers H8 and I I9, the spring I I1 being compressed a progressively increasing amount as the handle is progressively moved beyond the spool acting position without regard to the direction of such movement.

As an incident to this further movement of the handle I02 in either of its reverse directions with the consequent compression of the spring I, mechanism is brought into operation for adjusting progressively, and in accordance with the extent of movement of the handle I02, regardless of the direction of such movement, the pressure of the hydraulic fluid in the chamber I3 as determined by the pressure or relief valve 42. To this end the right hand web or plate I03 of each of the handles I02 is provided with a pair of downwardly extending radially spaced feet or legs I22. Each pair of feet or legs I22 straddles a roller I23 (see Figs. 3 and 5) there being five such rollers, all mounted on pivot pins on a pivoted bracket I24, the roller I23 being carried on upwardly extending bifurcated extensions I25 thereof (see Fig. 3). The bracket I24 is pivotally mounted on a pair of spaced brackets I (see Fig. 3) so that it can swing on a horizontal axis extending in front of the main valve assembly 43. The right hand end of the bracket I24 carries upper and lower rollers I2I which are mounted to roll on appropriate pivot pins and which abut a large head or disc I28 formed on the plunger 86.

The initial operation of the handle I02 to adjust the associated spool such as spool 45 does not produce any swinging movement of the bracket I24 since the legs I22 are radially spaced to provide for an abutting contact which takes place only following such valve spool shifting adjustment. Further movement, however, of the handle I02 in either direction Will cause one of the legs I22 to abut the associated roller I 23 and pivot the bracket I24 about its horizontal axis. This will cause one of the rollers I21 to move inwardly against the head I 28 since one of them is above the axis of the pivotal bracket I24 and the other is equally spaced below it, thus forcing the plunger 86 inwardly from the position illustrated in Fig. 5 which is the position of minimum hydraulic pressure for the system. This minimum pressure may be selected at any desired value, as for example 50 pounds per square inch, and may be adjusted progressively in infinite steps upon progressive movement of the handle I02 until a desired maximum pressure is reached which, purely for illustration, may be 1200 pounds per square inch. It is thus obvious that when a selected spool, such as spool 45, is thrown from its neutral position t start rotation of the hydraulic motors, such as the motors 35, it will first start under a minimum predetermined torque which is determined by the pressure of the hydraulic fluid delivered thereto. If the operator desires to increase the torque he merely pushes further on the handle I02 and this is true Whether he lifts it or pushes down on it or, in other words, regardless of the direction of operation of the hydraulic motors 35. Thus the operator can progressively increase the torque from the minimum starting value to any value within the range of the system.

From the foregoing it will be obvious that I have provided a hydraulic system and valve mech anism wherein the torque of driven motors, such as motors 3I and 35, may be adjusted startingfrom a minimum setting up to a maximum setting, as determined by the variable pressure in" the hydraulic system under the control of valve 42, as previously described. In other words, this variable torque or variable force feature provided by adjusting the pressure of its hydraulic fluid is useful not only in connection with the drivin wheels 28 and 29 but also in connection with the extension of the frame of the gathering head I9.

Obviously those skilled in the art may make various changes in the details and arrangement of parts without departing from the spirit and scope of the invention as defined by the claims hereto appended and applicant therefore Wishes not to be restricted to the precise construction herein disclosed.

Having thus described and shown an embodiment of the invention, what it is desired to secure by Letters Patent of the United States is:

1. In a loader, the combination with a frame, a pair of traction wheels supporting one end of said frame, means for supporting the other end of said frame for pivotal movement, said traction wheels being positionable in parallel relation to drive said loader longitudinally and in tandem relation to drive one end of the loader laterally while its other end pivots on said pivot means, separate motors for driving said wheels, and control means for said motors whereby said wheels may be driven together in reverse directions both in parallel and in tandem relations to drive the loader as aforesaid, said control mean including a hydraulic system having valve means operable selectively to reverse the direction of rotation of one of said motors relative to the other and to operate both of them in parallel.

2. In a loader, the combination with a frame, I

of a pair of traction wheels supporting one end of said frame, means for supporting the other end of said frame for pivotal movement, said traction wheels being positionable in parallel relation to drive said loader longitudinally and in tandem relation to drive one end of the loader laterally while its other end pivots on said pivot means, separate motors for driving said wheels, and control means for said motors whereby said wheels may be driven together in reverse directions both in parallel and in tandem relations to drive the loader as aforesaid, said control means including a hydraulic system having valve means operable selectively to reverse the direction of rotation of one of said motors relative to the other and to operate both of them.

3. In a loader, the combination with a frame, of a pair of traction wheels supporting one end of said frame, means for supporting the other end of said frame for pivotal movement, said traction wheels being positionable in parallel relation to drive said loader longitudinally and in tandem relation to drive one end of the loader laterally while its other end pivots on said pivot means, separate hydraulic motors for driving said wheels, and control means for said motors whereby said wheels may be driven together both in parallel and in tandem relations to drive the loader as aforesaid, said control means including a hy- 15 draulic system having valve means operable selectively to reverse the direction of rotation of one of said hydraulic motors relative to the other and to operate both said motors at variable speeds.

4. In a loader, the combination with a frame, of a pair of traction wheels supporting one end of said frame, means for supporting the other end of said frame for pivotal movement, said traction wheels being positionable in parallel relation to drive said loader longitudinally and in tandem relation to drive one end of the loader laterally while its. other end pivots on said pivot means, separate hydraulic motors for driving said wheels, and control means for said motors whereby said wheels may be driven together both in parallel and in tandem relations to drive the loader as aforesaid, said control means including a hydraulic system having valve means operable seleetively to reverse the direction of rotation of 0 onerof said hydraulic motors relative to the other and to operate both said motors at variable 16 speeds, said valve means including a control valve and a variable pressure relief valve operable from a single handle, the connection providing for operation of the control valve to open the circuit to the hydraulic motors when first moved from its neutral position and for increase in the pressure at which the hydraulic fluid delivered to said motors is relieved as the handle is progressively moved farther from said neutral position.

ARTHUR L. LEE.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,008,202 Schmucker Nov. 7, 1911 2,326,857 Holstein Aug. 1'7, 1943 2,393,324 Joy Jan. 22, 1946 2,527,943 Lee Oct. 31, 1950 2,589,827 Lee -s Mar. 18, 1952 

